1. Field of the Invention
The present invention relates to an apparatus for protecting the head and neck of an occupant onboard a vehicle subjected to a rear-end collision and particularly to a head and neck protection apparatus for vehicle suitable for use instead of a headrest in an automobile.
2. Description of the Related Art
Conventionally, if an automobile is subjected to a rear-end collision while an occupant is onboard, the head part of the occupant is strongly hit onto a headrest behind, and after that, the head part is largely thrown forward in many cases. And these continuous impacts both in forward and rearward directions might cause damages to the head and neck parts such as a bruise on the head part or cervical sprain called a whiplash injury.
In order to alleviate the above described rearward impact, Japanese Patent Laid-Open No. 2011-51526, for example, discloses an airbag device for head protection provided with an airbag embedded inside the headrest and inflated and deployed to a vehicle front side from the headrest; and a cushion material arranged in contact with a surface on the vehicle front side of the airbag inside the headrest and cleaved open at inflation/deployment of the airbag, in which the airbag has a main chamber inflated and deployed to the vicinity of the headrest or from the vicinity of the headrest to the vicinity of a shoulder portion of the seatback and a sub chamber extended in either one of or both of a vertical direction or a transverse direction of the main chamber. According to this Japanese Patent Laid-Open No. 2011-51526, it is described that, since the sub chamber is inflated and deployed in the vertical direction of the main chamber, the head part of the occupant can be protected for a wider range.
Moreover, Japanese Patent Laid-Open No. 11-262427 discloses a movable headrest in which an impact absorbing slit with a width smaller than a diameter of a support pin is provided in a reinforcing plate rotatably supporting the support pin of a ratchet plate in the movable headrest incorporating a ratchet mechanism composed of the ratchet plate rotatably provided on a headrest stay through the reinforcing plate and a lock member provided in a headrest frame so that a claw portion of this ratchet plate and a lock gear are meshed with each other. According to this Japanese Patent Laid-Open No. 11-262427, it is described that, when a collision accident such as a rear-end collision occurs in a vehicle, even if the head part of the occupant rapidly collides with the headrest, the support pin of the ratchet plate moves rearward while pushing open a slit width of the impact absorbing slit and thus, the headrest is plastically deformed as appropriate and retreats rearward, whereby a repulsion force to the head part of the occupant can be reduced, and an impact load applied to the head part of the occupant is effectively absorbed.